Histoplasmosis natural history, complications and prognosis

Histoplasmosis is an endemic fungal infection and infection occurs by inhalation of the microconidia present in the soil. The average incubation period is around 2 to 3 weeks. Majority of the patients are asymptomatic and few develop acute pulmonary histoplasmosis presenting with fever, cough and dyspnea. In immunocompetent patients the infection is self limiting and symptoms resolve in 2 to 3 weeks. However patients in immunocompromised state can have complications due to the spread of infection to other organs and develop disseminated histoplasmosis. Prognosis of disseminated histoplasmosis is poor and is associated with increased mortality.

The incubation period of histoplasmosis is typically 3–17 days for the acute disease. If left untreated immunocompromised patients can have complications such as pericarditis, broncholithiasis, pulmonary nodules, mediastinal granuloma, or mediastinal fibrosis. In persons who develop progressive, chronic, or disseminated disease, symptoms may persist for months or longer. Most people spontaneously recover 2–3 weeks after onset of symptoms, although fatigue may persist longer.^[1][2]

Some of the complications observed among patients with acute or chronic histoplasmosis include:^[3][4]

• Fibrosing mediastinitis
• Mediastinal granuloma
• Calcified lymph nodes
• Adrenal hyperplasia
• Macular degeneration (ocular histoplasmosis)
• Pericarditis
• Broncholithiasis
• Pulmonary nodules
• Disseminated histoplasmosis

Immunocompetent patients have excellent prognosis with symptoms resolving in 2 to 3 weeks. However, immunocompromised patients can have extensive spread of the infection and have poor prognosis. Mortality is high in HIV-infected persons who develop disseminated histoplasmosis and approximately 30% of HIV/AIDS patients diagnosed with histoplasmosis die from it.^[3][5]